Thanks John.
Some have suggested NOT to use a hole saw but instead a jig saw or sawzall.
Mostly because of tearing through roof shingles once it pokes through.
Thoughts on this?

Walter
"John Grabowski" wrote in message
...

"Walter Cohen" wrote in message
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Due to logistical reasons in my attic I need to route the new bathroom
fan exhaust duct up through the roof instead of out the side wall. It's
also a shorter run if I go vertically instead of horizontally.
I'll be buying 4" aluminum ducting so when I buy a hole saw to cut the
roof hole do I buy one that's 4" round, 4 1/4", or 4 1/2"?

Anything else I should do or watch out for?



I use a 4 1/4" hole saw in my angle drill at slow speed. You don't want
to go too fast with a puppy this big.